As a participating institution in the Primary Breast Cancer Therapy Group (NSABP), we are contributing data from patients entered into the various group protocols. We have made a major contribution (35 patients) to Protocol No. 6, which is a protocol to compare worth of segmental mastectomy with and without breast radiation with total mastectomy plus axillary dissection. All patients undergo axillary dissection and those with histologically positive axillary nodes receive adjuvant chemotherapy. Thirteen (13) patients have also been entered in Protocol No. 7, which evaluates L-PAM with L-PAM plus 5 FU; six (6) patients in Protocol No. 8, which is a trial to compare the worth of three-drug chemotherapy (L-PAM, 5 FU, and Methotrexate) with two-drug chemotherapy (L-PAM and 5 FU). We are also entering patients in Protocol No. 9: a trial to determine whether the anti-estrogen Tamoxifen when combined with chemotherapy improves the results obtained with chemotherapy alone, eighteen (18) patients so far have been entered in this newer Protocol. In the last 2 years, a total of 72 patients have been entered. Up until now we were financed on a subcontract basis. The present application seeks funding (a) to permit continued patient accrual in on-going protocols, (b) to continue follow up of patients entered into protocols which have terminated, and (c) to collect appropriate biological material and information relevant to such protocols. This group has the same capability to accomplish any new breast cancer protocol as it has done for the protocols already mentioned.